The qemu implementation of virConnectGetAllDomainStats in libvirt before 1.2.11 does not properly handle locks when a domain is skipped due to ACL restrictions, which allows a remote authenticated users to cause a denial of service (deadlock or segmentation fault and crash) via a request to access the users does not have privileges to access.
http://security.libvirt.org/2014/0008.html
http://lists.opensuse.org/opensuse-updates/2015-01/msg00005.html